I am looking for affordable boarding options on the San Francisco penninsula, especially something that I might not be able to find on bayareaequest. I'd love to also hear about any places from which I should stay far away! Ideally a field/pasture board situation but stalls are okay too (but turnout is important!). A private farm without a lot of ammenities would be fine. I prefer the Menlo Park/Woodside/Palo Alto area. I only need boarding for 3 months (end of May - end of August) as I'll be working in Palo Alto for the summer and I'd love to stay under $500/month. I ride hunter/jumpers but do not need an on site trainer. An arena (jumps?!?) would be a plus but just trails/pastures would be okay too.
Try Williams Ranch at La Honda. Its a bit hard to get to, but nice place with great pastures and arena. Not sure if they will let you in only for the summer, but its worth checking out. Keep checking Bayequest daily, good places are filled immediately. Another suggestion would be to see if they will let you in at CTETA horse park pasture, but you will have to pay membership fee.
There are also some private barns in the Woodside area that have openings. If you'd like, I can get some contact info for you.
Portola Pastures is nice but it has a waiting list. Pagemill Pastures has openings and access to trails and also has arenas where you can set up jumps. The only negative is they round the horses up with on weekends and some people aren't comfortable with that. The location is easy to get to as well.